Dressings, granules, and their use in treating wounds

ABSTRACT

This invention is directed to an occlusive dressing useful for treating skin lesions and a granular material capable of interacting with wound exudate. Wounds emitting a large amount of fluid can be treated by first packing with the granular material and then covering the wound with the occlusive dressing.

This is a continuation of co-pending application Ser. No. 370,893 filedon Apr. 22, 1982 now abandoned.

BACKGROUND OF THE INVENTION

Chen in U.S. Pat. No. 3,972,328 discloses a multi-layer surgicaldressing comprising an adhesive layer, a layer of flexible semi-opencell polymeric foam, and an outer water impervious flexible polymericfilm coating.

Steer et al. in published United Kingdom Patent Application No.2,061,732 disclose a multilayered dressing including a layer of curativeand absorbent material (B) which contacts the wound, a layer ofdeodorizing material (D), and an outer flexible layer (E) that securesthe bandage to the body. Layer (B) can be a homogeneous blend (11) ofone or more water soluble or swellable hydrocolloids dispersed in aviscous binder and affixed to a semi-open cell polymeric foam (13). Acritical feature of this dressing is that layer B has a plurality ofapertures (20) extending therethrough.

Chen in U.S. Pat. No. 3,339,546 discloses an adhesive compositioncomprising a blend of one or more water soluble or water swellablehydrocolloids and a viscous substance such as polyisobutylene. Theadhesive mass has a film of water insoluble material affixed to onesurface.

Chen et al. in U.S. Pat. No. 4,192,785 describe an adhesive compositionsuitable for use with an ostomy appliance consisting of a mixture of oneor more hydrocolloid gums, a pressure sensitive adhesive such as one ormore polyisobutylenes, and a cohesive strenghthening agent. The cohesivestrengthening agent can be a natural or synthetic fibrous material,finely divided cellulose, cross linked dextran, cross-linkedcarboxymethylcellulose, or a starch-acrylonitrile graft copolymer.

Steinhardt in U.S. Pat. No. 3,029,187 discloses an anhydrous powderblend of gelatin, pectin, and carboxymethylcellulose useful as anadhesive and in pharmaceutical preparations.

Rothman et al. in U.S. Pat. No. 4,225,580 discloses cleansing fluiddischarging skin surfaces by the use of a material comprising sphericalparticles of certain water-insoluble hydrophilic polymers.

SUMMARY OF THE INVENTION

This invention is directed to an occlusive dressing useful for treatingskin lesions such as dermal ulcers and pressure sores. This invention isalso directed to a method of treating skin wounds which are emitting alarge amount of fluid by packing the wound site with a unique granularmaterial and then covering the wound with the occlusive dressing. Astreatment progresses and the amount of liquid discharge lessens, thegranular packing material can be omitted.

This invention is also directed to the composition of the granularpacking material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall view of one embodiment of the composite dressing ofthis invention (greatly enlarged).

FIG. 2 is a front view along line 2--2 of FIG. 1.

FIG. 3 is an overall view of another embodiment of the compositedressing of this invention (greatly enlarged).

FIG. 4 is a front view along line 3--3 of FIG. 3.

FIG. 5 is an overall view of another embodiment of the compositedressing of this invention (greatly enlarged).

FIG. 6 is a front view along line 5--5 of FIG. 5.

FIG. 7 is a top view of an open wound covered by the dressing andpartially cut-away to show the granular packing.

DETAILED DESCRIPTION OF THE INVENTION THE DRESSING

One embodiment of the occlusive dressing 10 of this invention as shownin FIGS. 1 and 2 comprises a first adhesive layer 14 which is formulatedfrom materials selected to interact with fluid discharged from the woundas well as forming a fluid-tight bond with the healthy skin around thewound so as to seal the dressing to the skin. The dressing of thisembodiment includes a second adhesive layer 13 formulated of materialswhich can be cast onto foam layer 12 and will form an aggressive bondwhen pressed into contact with adhesive layer 14. The layer 12 is asemi-open cell elastic or flexible foam. The outer layer 11 can be apolymeric film or a skin formed on the top of foam layer 12 which servesto protect the exposed surface of the dressing from contamination bywater or soil.

An alternate embodiment of the occlusive dressing is shown as 30 inFIGS. 3 and 4. Dressing 30 includes a layer of deodorizing materialdesignated 31 interposed between adhesive layers 14 and 13.

Another alternate embodiment of the occlusive dressing is shown as 50 inFIGS. 5 and 6. Dressing 50 omits second adhesive layer 13 and hasadhesive layer 14 laminated directly to the semi-open cell elastic foam12.

Adhesive layer 14 comprises a homogeneous blend of one or more pressuresensitive adhesive materials and one or more water dispersiblehydrocolloidal materials. Adhesive layer 13 comprises a homogeneousblend of one or more pressure sensitive adhesive materials, one or morewater dispersible hydrocolloidal materials, a tackifier, and aplasticizer or solvent. Additionally, one or more thermoplasticelastomers may be included with the pressure sensitive adhesivematerials in either or both of layers 14 and 13 and one or more waterswellable cohesive strengthening agents and/or one or more natural orsynthetic polymers capable of developing elastomeric properties whenhydrated may be included with the hydrocolloidal materials in either orboth of layers 14 and 13.

Suitable pressure sensitive adhesive materials for inclusion in layers14 and 13 are various natural or synthetic viscous or elastomericsubstances such as natural rubber, silicone rubber, acrylonitrilerubber, polyurethane rubber, polyisobutylene, etc. Low molecular weightpolyisobutylenes having a viscosity average molecular weight of fromabout 36,000 to about 58,000 (Florey) possessing pressure sensitiveadhesive properties are preferred. Such polyisobutylenes arecommercially available under the trademark Vistanex from Exxon as gradesLM-MS and LM-MH.

Optionally, one or more thermoplastic elastomers can be included in thepressure sensitive adhesive component of layers 14 and 13. Theseelastomers impart the properties of rubber-like extensibility and bothrapid and complete recovery from modular strains to the pressuresensitive adhesive component. Suitable thermoplastic elastomers includemedium molecular weight polyisobutylenes having a viscosity averagemolecular weight of from about 1,150,000 to 1,600,000 (Florey), butylrubber which is a copolymer of isobutylene with a minor amount ofisoprene having a viscosity average molecular weight of from about300,000 to about 450,000 (Florey), and styrene copolymers such asstyrene-butadiene-styrene (S-B-S), styrene-isoprene-styrene (S-I-S), andstyrene-ethylene/butylene-styrene (S-EB-S) which are commerciallyavailable, for example, from Shell Chemical Co. under the trademarkKraton as Kraton D1100, D1102, Kraton D1107, Kraton 4000, Kraton G1600,and Kraton G4600. Preferred thermoplastic elastomers are butyl rubberhaving a viscosity average molecular weight of about 425,000(commercially available from Exxon as grade 077), polyisobutylene havinga viscosity average molecular weight of about 1,200,000 (commerciallyavailable under the trademark Vistanex from Exxon as grade L-100), andstyrene-isoprene-styrene (S-I-S) copolymers (commercially available fromShell as Kraton D1107).

The pressure sensitive adhesive component including the optionalthermoplastic elastomer is present in adhesive layers 14 and 13 at fromabout 30% to about 70% by weight of the composition, preferably fromabout 35% to about 50% by weight. The thermoplastic elastomer can beemployed at up to three times the weight of the pressure sensitiveelastomeric substances but preferably the theromoplastic elastomer ifpresent will be at from about 20% to about 150% by weight of thepressure sensitive elastomeric substance.

Adhesive layers 14 and 13 include from about 10% to about 65% by weightof one or more water dispersible hydrocolloid materials. Suitablehydrocolloid materials include sodium or calcium carboxymethylcellulose,pectin, gelatin, guar gum, locust bean gum, collagen and gum karaya.Adhesive layers 14 and 13 may also include up to about 50% by weight ofone or more water swellable cohesive strengthening agents and/or one ormore natural or synthetic polymers capable of developing elastomericproperties when hydrated provided that the water soluble hydrocolloidgums, water swellable cohesive strengthening agents, and hydratablepolymers together are present at no more than about 70% by weight ofadhesive layers 14 and 13. Suitable water swellable cohesivestrengthening agents include finely divided substantially waterinsoluble cross-linked sodium carboxymethylcellulose such as thatcommercially available under the trademark Aqualon or that described inU.S. Pat. No. 3,589,364 and available commercially from the BuckeyeCellulose Corp., finely divided substantially water insolublestarch-acrylonitrile graft copolymer such as that described in U.S. Pat.No. 3,661,815 and commercially available from the Grain ProcessingCorp., and finely divided substantially water insoluble cross-linkeddextran such as that commercially available under the trademarkSephadex. Suitably hydratable polymers are gluten and long chainpolymers of methyl vinyl ether/maleic acid, preferably, the long chainpolymers of methyl vinyl ether/maleic acid commercially available underthe trademark Gantrez from GAF Inc. The maleic acid moiety in thepolymer may be intact (Gantrez S-97), may be an anhydride (GantrezAN-169), or may be a metal salt such as the mixed sodium/calcium salts(Gantrez AT-955).

Preferably, the water dispersible hydrocolloids, the optional waterswellable cohesive strengthening agents, and the optional hydratablepolymers are present at from about 45% to about 65% by weight ofadhesive layer 14 and from about 30% to about 50% by weight of adhesivelayer 13.

The water dispersible hydrocolloids provide wet tack for adhesive layers14 and 13 while the pressure sensitive adhesive component provides dryadhesion and imparts structural integrity to layers 14 and 13.

Adhesive layer 13 also includes from about 5% to about 15% by weight ofa plasticizer or solvent such as mineral oil or petrolatum with mineraloil being preferred and from about 15% to about 25% by weight of atackifier such as a terpene resin.

Small amounts, i.e., less than 5% by weight, of other ingredients may beincluded within adhesive layers 14 and 13. For example, an antioxidantsuch as butylated hydroxyanisole or butylated hydroxytoluene, adeodorant such as chlorophyllins, or a perfume agent may be included. Inaddition, small amounts of a pharmacologically active ingredient can beincluded in adhesive layer 14. For example, an antibiotic orantimicrobial agent such as neomycin, an antiseptic agent such aspovidone iodine, and an antiinflammatory agent such as hydrocortisone ortriamcinolone acetonide.

The semi-open cell elastic or flexible foam layer 12 can be formed fromvarious elastomer materials such as polyester or polyether polyurethanefoams, styrene-butadiene foams, certain rubber based foam, etc. Thematerial should, of course, be non-toxic and stable. The preferredmaterial is a flexible polyurethane foam having from about 50 to about100 cells per linear inch with about 80 cells per linear inch being mostpreferred. By semi-open it is meant that the percentage of open orruptured cells is from about 30 to about 85%.

The outer layer 11 can be a polymeric elastic or flexible film coatingformed from a water impermeable pliable elastomer material such asflexible polyurethane, polyacrylate, polyethylene, etc. Layer 11 can bea skin of such polymeric material flame laminated to the top of foamlayer 12 by means of heat and/or pressure. The exposed sides ofpolymeric foam layer 12 can also be coated or heat and/or pressuretreated to form an impermeable film or skin. Polyurethane is thepreferred material for film or skin 11.

In a typical dressing, adhesive layer 14 will vary in thickness fromabout 0.02 to about 0.1 inches, preferably about 0.05 inches, adhesivelayer 13 will vary in thickness from about 0.005 to about 0.02 inches,preferably about 0.015 inches, foam layer 12 will vary in thickness fromabout 0.03 to about 0.1 inches, preferably about 0.065 inches and outerlayer or skin 11 will vary in thickness from about 0.001 to about 0.003inches, preferably about 0.002 inches.

As shown in FIGS. 3 and 4, a layer of deodorizing material can beincluded between the two adhesive layers. Suitable deodorizing materialsinclude a sheet of foamed polymeric material such as polyurethane havinga large number of activated carbon particles bound to the matrix of thefoam. Such a material is commercially available under the tradenameBondina. Another type of deodorizing material is a paper or felt likesubstance containing activated carbon such as that commerciallyavailable under the tradename K-felt (Toyobo) or Getter paper (Mead).The layer of deodorizing material will vary from about 0.010 to 0.100inches.

The dressing 10 is prepared as follows. First, adhesive layer 14 isprepared by forming a homogeneous dispersion of the pressure sensitiveadhesive material and any thermoplastic elastomer with a heavy dutymixer, e.g., a kneader mixer or sigma blade mixer. The hydrocolloidgums, water swellable cohesive strengthening agents, hydratablepolymers, and any other optional ingredients are added and mixing iscontinued until a homogeneous dough is formed. Alternatively, if layer14 includes a thermoplastic elastomer, then the elastomer can first bebroken down by mixing for several minutes, a portion of the pressuresensitive adhesive material and other ingredients added and mixingcontinued until a homogeneous mass is formed. The balance of pressuresensitive adhesive is then added and the mixing continued until ahomogeneous dough is formed. This dough is then extruded into a thickslab which is thinned down by pressure rollers to the desired thickness.

Next, adhesive layer 13 is prepared by forming a mixture of thehydrocolloid gums, pressure sensitive adhesive materials, tackifier andplasticizer, as well as other optional ingredients such as thermoplasticelastomers, water swellable cohesive strengthening agents, hydratablepolymers, antioxidants, etc., in an organic solvent such as heptane orhexane. The resulting adhesive slurry is then applied to a web ofsilicone coated release paper and the solvent is evaporated. Upon dryingthe hydrocolloids are dispersed throughout the adhesive layer. Thisadhesive material is then compressed with a laminate of semi-open cellflexible polymeric foam having a water impermeable polymeric coating orskin on one side.

Finally, the silicone coated release paper is stripped away fromadhesive layer 13 and adhesive layers 13 and 14 are pressed togetherwith heat to form the dressing. Silicone coated release paper can thenbe applied to the exposed surface of adhesive layer 14 and the dressingcan be cut to the desired shape and packaged. After packaging, thedressing can be sterilized by gamma irradiation.

Dressing 30 is prepared in a similar manner except that a layer ofdeodorizing material is laminated between adhesive layers 14 and 13.Alternatively, dressing 30 can be prepared by first laminating adhesivelayer 13 directly to the layer of deodorizing material 31 and thenattaching this adhesive coated material to foam layer 12. In the case ofdressing 50, adhesive layer 14 is prepared as described above and isthen laminated while warm directly to foam layer 12 by means ofpressure.

The following are representative examples of dressings within the scopeof the invention.

EXAMPLE 1

A dressing was prepared having the following composition

Layers 11 and 12

Semi-open cell polyurethane foam having a polyurethane skin flamelaminated to one surface.

    ______________________________________                                                          Percent by weight                                           ______________________________________                                        Layer 13                                                                      Polyisobutylene     18.0                                                      (Vistanex LM-MH)                                                              Polyisobutylene     20.0                                                      (Vistanex L-100)                                                              Terpene resin       20.0                                                      (Piccolyte)                                                                   Butylated hydroxytoluene                                                                          0.5                                                       Mineral oil         8.5                                                       Sodium carboxymethylcellulose                                                                     18.0                                                      Gelatin             15.0                                                      Layer 14                                                                      Polyisobutylene     40                                                        (Vistanex LM-MH)                                                              Gelatin             20                                                        Pectin              20                                                        Sodium carboxymethyl-                                                                             20                                                        cellulose                                                                     ______________________________________                                    

Adhesive layer 14 was prepared as follows. A premix was prepared byblending 1.4 kg. of gelatin, 1.4 kg. of pectin, and 1.4 kg. of sodiumcarboxymethylcellulose. The blended premix was added to a heavy dutysigma bladetype mixer followed by the addition of 1.4 kg. ofpolyisobutylene. After mixing for 10 minutes, an additional 1.4 kg. ofpolyisobutylene was added and mixing continued until a homogeneous doughwas formed (about 10 to 20 minutes). This dough mass while hot and softwas extruded and thinned down by pressure rollers to a thickness ofabout 0.05 inches.

A laminate of adhesive layer 13 to semiopen cell polymeric foam (layers12 and 11) was prepared as follows.

A mixture of 0.31 kg. of polyisobutylene (Vistanex L-100), 0.28 kg. ofsodium carboxymethylcellulose, and 0.23 kg. of gelatin was kneaded. Thismixture was added to a solution of heptane containing 0.28 kg. ofpolyisobutylene (Vistanex LM-MH), 0.31 kg. of piccolyte resin, 8 g. ofbutylated hydroxytoluene, and 0.13 kg. of mineral oil to form anadhesive slurry. A portion of this slurry was poured onto a sheet ofsilicone coated release paper and the solvent evaporated to leave anadhesive layer of about 0.015 inches in thickness. This adhesive layerwas laminated to a semi-open cell polyurethane foam of 0.065 inchesthickness having a polyurethane skin of about 0.002 inches thickness onone surface by gently compressing the adhesive layer to the foam bypassing through pressure rollers.

The silicone coated release paper was then stripped from adhesive layer13 and adhesive layer 13 and adhesive layer 14 were compressed togetherby passing through pressure rollers. Silicone coated release paper wasthen pressed onto the exposed surface of adhesive layer 14. Theresulting dressing was cut into the desired shape and packaged.

EXAMPLES 2-15

Following the procedure of Example 1 but employing the followingingredients on a weight percent basis in adhesive layer 14 otherdressings within the scope of this invention are obtained.

    __________________________________________________________________________                      Example                                                     Ingredient         2                                                                               3                                                                              4   5                                                                               6                                                                               7                                                                               8                                                                               9                                                                              10                                                                              11                                                                              12                                                                              13                                                                              14                                                                              15                               __________________________________________________________________________    Polyisobutylene (Vistanex LM-MH)                                                                40                                                                              40                                                                              40 40                                                                              40                                                                              40                                                                              45                                                                              50                                                                              20                                                                              30                                                                              20                                                                              40                                                                              40                                                                              40                               Guar gum          25                                                                              60                                                                              -- 25                                                                              30                                                                              30                                                                              25                                                                              --                                                                              20                                                                              --                                                                              20                                                                              --                                                                              20                                                                              --                               Locust bean gum   --                                                                              --                                                                              -- --                                                                              --                                                                              --                                                                              --                                                                              20                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              20                               Pectin            --                                                                              --                                                                              -- --                                                                              --                                                                              --                                                                              15                                                                              --                                                                              --                                                                              15                                                                              --                                                                              15                                                                              --                                                                              20                               Karaya            --                                                                              --                                                                              -- --                                                                              --                                                                              --                                                                              --                                                                              20                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                               Gelatin           --                                                                              --                                                                              -- --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              15                                                                              --                                                                              15                                                                              --                                                                              --                               Sodium carboxymethylcellulose                                                                   10                                                                              --                                                                              17.2                                                                             10                                                                              12                                                                              --                                                                              --                                                                              --                                                                              10                                                                              15                                                                              20                                                                              15                                                                              15                                                                              10                               Collagen          --                                                                              --                                                                              -- --                                                                              --                                                                              10                                                                              --                                                                              --                                                                              10                                                                              --                                                                              --                                                                              15                                                                              15                                                                              --                               Cross-linked sodium carboxymethyl-                                                              15                                                                              --                                                                              25.6                                                                             15                                                                              18                                                                              --                                                                              --                                                                              --                                                                              15                                                                              10                                                                              --                                                                              --                                                                              10                                                                              --                               cellulose (Aqualon R)                                                         Starch-acrylonitrile graft                                                                      --                                                                              --                                                                              -- --                                                                              --                                                                              --                                                                              15                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              10                               copolymer (Grain Processing                                                   Corp. Polymer 35-A-100)                                                       Cross-linked dextran                                                                            --                                                                              --                                                                              -- --                                                                              --                                                                              --                                                                              --                                                                              10                                                                              --                                                                              --                                                                              20                                                                              --                                                                              --                                                                              --                               (Sephadex CM-C50)                                                             Poly(methyl vinyl ether/                                                                        10                                                                              --                                                                              17.2                                                                             10                                                                              --                                                                              20                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                               maleic acid), mixed calcium,                                                  sodium salt (Gantrez AT-955)                                                  Polyisobutylene (Vistanex L-100)                                                                --                                                                              --                                                                              -- --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              25                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                               Butyl rubber (grade 077)                                                                        --                                                                              --                                                                              -- --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              15                                                                              --                                                                              --                                                                              --                                                                              --                               Styrene-isoprene copolymer                                                                      --                                                                              --                                                                              -- --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              20                                                                              --                                                                              --                                                                              --                               (Kraton 1107)                                                                 __________________________________________________________________________

Following the procedure of Example 1 but employing the ingredientslisted below on a weight percent basis in adhesive layer 13 otherdressings within the scope of this invention are obtained.

    __________________________________________________________________________                      Example                                                     Ingredient        16 17 18                                                                              19 20 21                                                                              22                                                                              23                                        __________________________________________________________________________    Polyisobutylene (Vistanex LM-MH)                                                                15 15 15                                                                              15 15 15                                                                              20                                                                              15                                        Guar gum          20 15 --                                                                              -- 15 15                                                                              25                                                                              --                                        Locust bean gum   -- -- 17                                                                              -- -- --                                                                              --                                                                              --                                        Pectin            -- -- --                                                                              10 -- --                                                                              --                                                                              --                                        Karaya            -- -- --                                                                              -- -- --                                                                              --                                                                              10                                        Gelatin           -- -- --                                                                              10 -- --                                                                              --                                                                              --                                        Sodium carboxymethylcellulose                                                                   15 15 10                                                                              10 10 --                                                                              --                                                                              15                                        Collagen          -- -- --                                                                              -- -- --                                                                               5                                                                              --                                        Cross-linked sodium carboxymethyl-                                                              -- 15 --                                                                              -- -- 10                                                                              --                                                                              --                                        cellulose (Aqualon R)                                                         Starch-acrylonitrile graft                                                                      -- -- --                                                                              -- 10 --                                                                              --                                                                              --                                        copolymer (Grain Processing                                                   Corp. Polymer 35-A-100)                                                       Cross-linked dextran                                                                            -- -- --                                                                              10 -- --                                                                              --                                                                              10                                        (Sephadex CM-C50)                                                             Poly(methyl vinyl ether/                                                                        -- -- 10                                                                              -- -- 10                                                                              --                                                                              --                                        maleic acid), mixed calcium,                                                  sodium salt (Gantrez AT-955)                                                  Polyisobutylene (Vistanex L-100)                                                                -- -- 20                                                                              15 20 20                                                                              15                                                                              20                                        Butyl rubber (grade 077)                                                                        20 -- --                                                                              -- -- --                                                                              --                                                                              --                                        Styrene-isoprene copolymer                                                                      -- 19.5                                                                             --                                                                              -- -- --                                                                              --                                                                              --                                        (Kraton 1107)                                                                 Mineral oil       9.5                                                                               5 7.5                                                                             9.5                                                                              9.5                                                                              9.5                                                                             9.5                                                                             9.5                                       Piccolyte resin   20 15 20                                                                              20 20 20                                                                              25                                                                              20                                        Butylated hydroxytoluene                                                                        0.5                                                                               0.5                                                                             0.5                                                                             0.5                                                                              0.5                                                                              0.5                                                                             0.5                                                                             0.5                                       __________________________________________________________________________

THE GRANULES

The wound packing material is a granular product of from about 10 toabout 40 mesh particle size and comprises a water dispersablehydrocolloidal material or a mixture of such materials. The granularproduct can also optionally include up to about 50% by weight of one ormore water swellable cohesive strengthening agents and/or one or morehydratable polymers. Suitable water dispersible hydrocolloidal materialsinclude sodium and calcium carboxymethylcellulose, pectin, gelatin, guargum, locust bean gum, collagen, and gum karaya. Suitable water swellablecohesive strengthening agents include finely divided substantially waterinsoluble crosslinked sodium carboxymethylcellulose such as thatcommercially available under the trademark Aqualon or that described inU.S. Pat. No. 3,589,364 and available commercially from the BuckeyeCellulose Corp., finely divided substantially water insolublestarch-acylonitrile graft copolymer such as that described in U.S. Pat.No. 3,661,815 and commercially available from the Grain ProcessingCorp., and finely divided substantially water insoluble cross-linkeddextran such as that commercially available under the trademarkSephadex. Suitably hydratable polymers are gluten and long chainpolymers of methyl vinyl ether/maleic acid, preferably, the long chainpolymers of methyl vinyl ether/ maleic acid commercially available underthe trademark Gantrez from GAF Inc. The maleic acid moiety in thepolymer may be intact (Gantrez S-97), may be an anhydride (GantrezAM-169), or may be a metal salt such as the mixed sodium/calcium salts(Gantrez AT-955).

Small amounts, i.e., less than 5% by weight, of other ingredients may beincluded within or sprayed onto the granules. For example, anantioxidant such as butylated hydroxyanisole or butylatedhydroxytoluene, a deodorant such as chlorophyllins, or a perfume agentmay be included. In addition, small amounts of a pharmacologicallyactive ingredient can be included within or sprayed onto the granules.For example, an antibiotic or antimicrobial agent such as neomycin, anantiseptic agent such as povidone iodine, and an antiinflammatory agentsuch as hydrocortisone or triamcinolone acetonide.

The granules preferably contain at least 70% by weight of one or morewater dispersible hydrocolloids selected from pectin, gelatin, sodiumcarboxymethylcellulose, and collagen with a granular product consistingof an equal weight percent mixture of pectin, gelatin, and sodiumcarboxymethylcellulose being most preferred.

The granular material can be prepared from the powder ingredients by drycompaction, wet granulation, or fluidized bed granulation techniques.The dry compaction method involves blending the component powders,compacting into a slab, and milling the slab to the desired particlesize. The milled material is sieved and particles of the proper sizerange are gathered and packaged.

In the wet granulation process, the powders after blending, orsimultaneously with blending, are moistened with water, a hydroalcoholicsolution, or low concentration dispersion of one or more of the waterdispersable hydrocolloids in water or hydroalcoholic vehicles. Normally,the amount of moisture added is up to about 50% of the dry weight of thepowders in order to form granules with adequate process-ability andresistance to attrition. After thorough mixing, the moistened mass isforced through a screen or die to yield granules directly or to yield byextrusion, a particulate noodle-like or ribbon-like mass of material.When dried, this material is then milled to the desired sieve size andpackaged. Alternatively, the moistened mass may first be broken intolarge lumps which are then dried and milled to the desired particlesize.

In the fluid bed granulation procedure, the moistening fluid is added toa charge of the blended powders held suspended on a column of risingwarm air where the powders are allowed to mix with the granulatingfluid, which is very rapidly evaporated, leaving behind agglomeratedgranules. Less moistening fluid is required in this process then in thewet granulation process described above.

EXAMPLE 24

To 120 kg. of a mixture of equal parts of gelatin, pectin and sodiumcarboxymethylcellulose were added about 50 liters of distilled water ora mixture of water and ethanol. Mixing was performed in a rotatingoscillating device to produce a homogeneous blend. The blend wasscreened through a coarse sieve (0.5 inch) and the moistened materialwas dried at 55° C. for 24 hours. The dried material was milled andscreened to between 16 and 20 mesh.

EXAMPLES 25-35

Following the procedure of Example 24 but employing the ingredientslisted below on a weight percent basis other granular products withinthe scope of this invention are obtained.

    __________________________________________________________________________                      Example                                                     Ingredient        25                                                                              26                                                                              27                                                                              28                                                                              29                                                                              30 31                                                                              32                                                                              33                                                                              34                                                                              35                                     __________________________________________________________________________    Guar gum          --                                                                              --                                                                              --                                                                              --                                                                              20                                                                              -- --                                                                              --                                                                              --                                                                              --                                                                              --                                     Locust bean gum   --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              -- 20                                                                              --                                                                              --                                                                              --                                                                              --                                     Pectin            25                                                                              50                                                                              --                                                                              --                                                                              20                                                                              23.3                                                                             --                                                                              20                                                                              20                                                                              25                                                                              20                                     Karaya            --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              -- 20                                                                              --                                                                              --                                                                              --                                                                              --                                     Gelatin           25                                                                              --                                                                              50                                                                              --                                                                              --                                                                              23.3                                                                             --                                                                              20                                                                              20                                                                              25                                                                              20                                     Sodium carboxymethylcellulose                                                                   25                                                                              --                                                                              --                                                                              50                                                                              40                                                                              23.4                                                                             60                                                                              20                                                                              20                                                                              25                                                                              20                                     Calcium carboxymethylcellulose                                                                  --                                                                              --                                                                              --                                                                              --                                                                              20                                                                              -- --                                                                              --                                                                              --                                                                              --                                                                              --                                     Collagen          25                                                                              50                                                                              50                                                                              50                                                                              --                                                                              -- --                                                                              20                                                                              10                                                                              --                                                                              20                                     Cross-linked sodium carboxymethyl-                                                              --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              20 --                                                                              --                                                                              --                                                                              25                                                                              20                                     cellulose (Aqualon R)                                                         Starch-acrylonitrile graft                                                                      --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              -- --                                                                              20                                                                              --                                                                              --                                                                              --                                     copolymer (Grain Processing                                                   Corp. Polymer 35-A-100)                                                       Cross-linked dextran                                                                            --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              -- --                                                                              --                                                                              20                                                                              --                                                                              --                                     (Sephadex CM-C50)                                                             Poly(methyl vinyl ether/                                                                        --                                                                              --                                                                              --                                                                              --                                                                              --                                                                              10 --                                                                              --                                                                              10                                                                              --                                                                              --                                     maleic acid), mixed calcium,                                                  sodium salt (Gantrez AT-955)                                                  __________________________________________________________________________

METHOD OF TREATING SKIN WOUNDS

The use of the occlusive dressings described above results in a closedmoist wound treatment environment. Unlike gauze type dressings, theingredients employed in adhesive layer 14 permit the dressings of thisinvention to remain in place over the wound for up to several days. Itis believed that the need to frequently change a dressing disturbs thewound healing environment and results in a slower healing process.

The water dispersible hydrocolloid materials, the water swellablecohesive strengthening agents, and the hydratable polymers distributedthroughout adhesive layer 14 react in the presence of moisture. In thearea of normal skin surrounding the wound site, the layer 14 willgradually hydrate over a period of days. The initial aggressive bond ofthe dressing to this normal skin is due to the presence of the pressuresensitive adhesive materials in layer 14; i.e., dry tack. As this bondis lessened by perspiration and leakage of moisture under layer 14, thewet tack of the moisture active ingredients in layer 14 becomes morecritical in bonding the dressing to the skin. Eventually, layer 14becomes so hydrated that the dressing can be removed without strippingor macerating the skin around the wound site.

When the dressing is applied over a fluid emitting wound such as adermal ulcer, it has been observed that the moisture active ingredientsin layer 14 will be converted to an almost gellike mass. This providesan ideal moist environment for cell migration ensuring easy dressingremoval with a minimum of damage to the newly formed tissues.

In treating ulcers emitting a large volume of exudate, it has been foundto be useful to first pack the wound with the granular materialdescribed above and then cover with the occlusive dressing. The granulesinteract with the wound exudate to form a gel-like mass and preventleakage through the dressing. As a result, the dressing is changed lessoften which is believed to result in a shortened healing period. Afterremoval of the dressing, the hydrated granules can be removed from thewound site by flushing with saline solution. As healing progresses andless exudate is present in the sound site , the dressing can be employedwithout the granular packing.

FIG. 7 shows an ulcer 70 covered by occlusive dressing 10. The dressingis partially broken away to show the granular packing material 75. Ofcourse, adhesive layer 14 contacts the granules 75 in the area of thewound and also bonds the dressing to the normal skin 71 surrounding theulcer.

What is claimed is:
 1. An occlusive multi-layered wound dressingconsisting essentiallly of an adhesive layer which in use contacts thewound and the surrounding normal skin, an intermediate layer ofsemi-open cell polymeric foam bonded to the upper surface of saidadhesive layer, and an outer moisture impervious polymeric film coatedor laminated to the upper surface of said foam layer, wherein said woundand skin contacting adhesive layer consists of from about 35% to about50% by weight of low molecular weight polyisobutylenes and from about45% to about 65% by weight of one or more water dispensiblehydrocolloids selected from the group consisting of sodiumcarboxymethylcellulose, calcium carboxymethylcellulose, pectin, gelatin,guar gum, locust bean gum, collagen, and gum karaya.
 2. The dressing ofClaim 1 wherein said wound and skin contacting adhesive layer is ahomogeneous blend of about 40% by weight of low molecular weightpolyisobutylene, about 20% by weight of sodium carboxymethylcellulose,about 20% by weight of pectin, and about 20% by weight of gelatin. 3.The dressing of Claim 2 wherein said semi open-cell polymeric foam ispolyurethane foam and said water impervious polymeric film ispolyurethane.
 4. The dressing of Claim 3 wherein said wound and skincontacting adhesive layer is from about 0.02 to about 0.1 inches inthickness, said polyurethane foam layer is about 0.03 to about 0.1inches in thickness, and said water impervious polyurethane layer isabout 0.001 to about 0.003 inches in thickness.
 5. An occlusivemulti-layered wound dressing consisting essentially of an adhesive layerwhich in use contacts the wound and the surrounding normal skin, saidadhesive layer being from about 0.02 to about 0.1 inches in thickness,an intermediate layer of semi-open cell polyurethane foam bonded to theupper surface of said adhesive layer, said foam layer being from about0.03 to about 0.1 inches in thickness, and an outer moisture imperviouspolyurethane film coated or laminated to the upper surface of said foamlayer, said film being from about 0.001 to about 0.003 inches inthickness, wherein said wound and skin contacting adhesive layer is ahomogeneous blend of about 40% by weight of low molecular weightpolyisobutylene, about 20% by weight of sodium carboxymethylcellulose,about 20% by weight of pectin, and about 20% by weight of gelatin.
 6. Anocclusive multi-layered wound dressing consisting essentially of a firstadhesive layer which in use contacts the wound and the surroundingnormal skin, a second adhesive layer bonded to the top surface of saidfirst adhesive layer, an intermediate layer of semi-open cell polymericfoam bonded to the upper surface of said second adhesive layer, and anouter moisture impervious polymeric film coated or laminated to theupper surface of said foam layer, wherein said first adhesive layerconsists of from about 35% to about 50% by weight of low molecularweight polyisobutylene and from about 45% to about 65% by weight of oneor more water dispersible hydrocolloids selected from the groupconsisting of sodium carboxymethylcellulose, calciumcarboxymethylcellulose, pectin, gelatin, guar gum, locust bean gum,collagen, and gum karaya and wherein said second adhesive layer consistsof from about 35% to about 50% by weight of low molecular weightpolyisobutylenes and one or more optional thermoplastic elastomersselected from the group consisting of medium molecular weightpolyisobutylenes, butyl rubber, and styrene-isoprene-styrene copolymers,from about 30% to about 50% by weight of one or more water dispersiblehydrocolloids selected from the group consisting of sodiumcarboxymethylcellulose, calcium carboxymethylcellulose, pectin, gelatin,guar gum, locust bean gum, collagen, and gum karaya, from about 5% toabout 15% by weight of mineral oil, from about 15% to about 25% byweight of a terpene resin tackifier, and less than about 5% by weight ofone of more antioxidants, deodorants, and perfume agents.
 7. Thedressing of Claim 6 wherein said wound and skin contacting firstadhesive layer is a homogeneous blend of about 40% by weight of lowmolecular weight polyisobutylene, about 20% by weight of sodiumcarboxymethylcellulose, about 20% by weight of pectin, and about 20% byweight of gelatin.
 8. The dressing of Claim 7 wherein said secondadhesive layer is a homogeneous blend of from about 18% by weight of lowmolecular weight polyisobutylenes, about 20% by weight of mediummolecular weight polyisobutylenes, about 18% by weight of sodiumcarboxymethylcellulose, about 15% by weight of gelatin, about 20% byweight of terpene resin, about 8.5% by weight of mineral oil, and about0.5% by weight butylated hydroxytoluene.
 9. The dressing of Claim 8wherein said semi open-cell polymeric foam is polyurethane foam and saidwater impervious polymeric film is polyurethane.
 10. The dressing ofClaim 9 wherein said wound and skin contacting first adhesive layer isfrom about 0.02 to about 0.1 inches in thickness, said second adhesivelayer is from about 0.005 to about 0.02 inches in thickness, saidpolyurethane foam layer is about 0.03 to about 0.1 inches in thickness,and said water impervious polyurethane layer is about 0.001 to about0.003 inches in thickness.
 11. An occlusive multi-layered wound dressingconsisting essentially of a first adhesive layer which in use contactsthe wound and the surrounding normal skin, said first adhesive layerbeing of from about 0.02 to about 0.1 inches in thickness, a secondadhesive layer bonded to the top surface of said first adhesive layer,said second adhesive layer being from about 0.005 to about 0.02 inchesin thickness, an intermediate layer of semi-open cell polyurethane foambonded to the upper surface of said second adhesive layer, said foambeing from about 0.03 to about 0.1 inches in thickness, and an outermoisture impervious polyurethane film coated or laminated to the uppersurface of said foam layer, said film being from about 0.001 to about0.003 inches in thickness, wherein said wound and skin contacting firstadhesive layer is a homogeneous blend of about 40% by weight of lowmolecular weight polyisobutylene, about 20% by weight of sodiumcarboxymethylcellulose, about 20% by weight of pectin, and about 20% byweight of gelatin, and wherein said second adhesive layer is ahomogeneous blend of from about 18% by weight of low molecular weightpolyisobutylenes, about 20% by weight of medium molecular weightpolyisobutylenes, about 18% by weight of sodium carboxymethylcellulose,about 15% by weight of gelatin, about 20% by weight of terpene resin,about 8.5% by weight of mineral oil, and about 0.5% by weight ofbutylated hydroxytoluene.